Atomic and Molecular Mass

Which of the following has least mass?

The common isotopes of carbon are ${}^{12}\mathrm{C}$ and ${}^{13}\mathrm{C}$. The average mass of carbon is $12.01115 \mathrm{amu}$. What is the abundance of the ${}^{13}\mathrm{C}$ isotope?

Which atom was originally used as a reference element for defining the atomic masses of other atoms.

Oxygen as a reference element was rejected because oxygen has other isotopes as well.

The relative atomic mass of nitrogen assuming oxygen as the reference element is

Define amu assuming oxygen as the reference element.

Calculate the atomic mass of nitrogen assuming oxygen as the reference element.

Which element is used as a reference element in the present system of atomic masses?

What is the difference between mass number and relative atomic mass?

Carbon- _____ is the reference for all atomic mass calculations. ($10/11/12$)

Is hydrogen the standard for atomic mass?

An element X has the following isotopic composition:
${}^{200}\mathrm{X}:90\raisebox{1ex}{$ \mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,  ${}^{199}\mathrm{X}:8.0 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,   ${}^{202}\mathrm{X}:2 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$
The weighted average atomic mass of the naturally occurring element X is close to

An element X has the following isotopic composition:
${}^{200}\mathrm{X}:90\raisebox{1ex}{$ \mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,  ${}^{199}\mathrm{X}:8.0 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$ ,   ${}^{202}\mathrm{X}:2 \raisebox{1ex}{$\mathrm{o}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{o}$}\right.$
The weighted average atomic mass of the naturally occurring element X is close to

Average atomic mass of $\mathrm{Mg}$ is approximately equal to. (Given that percentage abudance of ${{12}^{\mathrm{Mg}}}^{24}$, ${{12}^{\mathrm{Mg}}}^{25}$ and ${{12}^{\mathrm{Mg}}}^{26}$ are $79\%, 10\% \mathrm{and} 11\%$, respectively)

What will be the effect on mass of one mole of substance, if we consider 1/6, in place of 1/12 of mass of carbon atom as relative atomic mass unit?

Suppose 1/4^th part by weight of an atom of He⁴ isotope is taken as 1u rather than the present convention, then what will be the expected atomic weight of Al on this scale? (Atomic weight of Al, C and He on C¹² - scale are 27, 12 and 4.003 respectively)

Let  $‘\mathrm{A}’$ be the methyl ester of an organic monocarboxylic acid. The vapour density of  $‘\mathrm{A}’$ is $37$. What is the molecular weight of the acid?

A mixture contains ${\mathrm{N}}_2{\mathrm{O}}_4$ and $\mathrm{N}{\mathrm{O}}_2$ in 2 : 1 ratio by volume. The vapour density of the mixture is

Chorine exists in two isotopic forms, Cl-37 and Cl-35 but its atomic mass is 35.5. This indicates the ratio of Cl-37 and Cl-35 is approximately